Methods and devices for examining the flatiness or the exactly concentric cylinder-shape of a plane or cylindric surface, e. g. the active surface of printing-forms and/or of the supporting member thereof



Dec. 22, 1964 M. CAHEN 3,162,040

METHODS AND DEVICES FOR EXAMINING THE FLATNESS OR THE EXACTLY coNcENTRIcCYLINDER-SHAPE OF A PLANE 0R CYLINDRIC SURFACE, E.G. THE ACTIVE SURFACEOF PRINTING-FORMS AND/0R OF THE SUPPORTING MEMBER THEREOF Filed May 24,1961 INVENIOR BY I 254 ATTORNEY United States Patent 3,162 640 METHODSAND DEVIQES FOR EXAMKNING THE FLATNESS OR THE EXACTLY CGNQENTREE ClldDhlt-SfiAPE UF A PLANE GR (IYLENDRIC SURFACE, E.G. THE AQTWE SURFAIJE0F PRiNTlNG-FGRMS AND/0R THE dUPPGRT- ENG NEE BEER TIEREGF Max Cahen,iapierstraat 6-8, s-Hertogenhesch, Netherlands Filed May 24, B61, Ser.No. 112,427 Claims priority, application Netherlands May 28, 1969 9Claims. (iii. TS-Hi4) The invention relates to a method and an apparatusexamining the flatness or the exactly concentric cylindershape of aplane or cylindric surface, e.g. the active surface of a flat orcylindric supporting member and/ or a layer or plate provided on such asupporting member, such as a layer or plate provided withprinting-forms, by means of a colouring-matter, which is applied in athin film by means of a roller on the surface to be tested.

In the printing-technique several methods and devices for the abovemeant examination are used. For instance it has already been proposed touse a micro-meter adapted to be moved over a surface plate or along adescriptive line of a cylinder, by means of which micro-meter atopographical diagram of the height variations of the active surface ofthe printing-form was made by scanning the latter point by point. Thiswork takes up much time, and has moreover an unsatisfactory result, ifthe printingblocks or printing-forms are made from material having aconsiderable elasticity, since in that case the local deformation due tothe pressure of the micro-meter is often greater than the permissiblevariations of the examined surface. That is why in fiat-bed printingmostly a test printing-press is used, by means of which a test print ismade on paper or other foil from the plate supporting the printing-formsunder circumstances which imitate the operating conditions as close aspossible. The hollow spots of the active surface of the printing-formsthen give a too light print or no print at all. The topographicaldiagram of the printing surface is obtained in mirror image on anothercarrier. Both the latter fact and the necessity to use a test press andto have to clean the printing-forms and the ink-device time and againinvolve difficulties.

According to a third method a roller of rigid material and carrying athin layer of ink is rolled over the printing form, in such a manner,that the hollow spots of the printing-form do not take up ink at all orare inked too little. The disadvantages of this method are that it isvery difiicult toapply an ink-film of constant thickness onto the rollerand that after each examination the printingform and the ink roller mustbe carefully cleaned which still does not prevent that the printing-formis gradually tinted.

Even if the printing plate should have a constant thickness in theplaces of the printing-elements there is .no guarantee that after theprinting plate has been mounted on the plane or cylindric supportingmember a satisfactory print can be made therefrom. For instance, thetwo-sided adhesive tape used for the attachment may have variations inthickness. Further, the supporting member may be not entirely fiat orcylindric or slightly eccentric to the axis. Also bending of theprinting plate arond the cylindric surface may produce faults.

The invention has for its object to produce a simple method andapparatus, by means of which not only the flatness or the exactlyconcentric cylinder-shape of the surface of a flat or cylindric body butalso the surface conditions of a plate or layer, e.g. a plate providedwith printing-forms, mounted on such a body can be easily hid-2,4Patented Eec. 22, 1964 "Ice examined, whereas the disadvantages of theknown methods and devices are thereby entirely avoided. Said methodconsists in that as colouring-matter a dry powder is used. It hasappeared that dry powder is easily ap plied on a roller in a layer,which has in every place exactly the desired thickness. Moreover, powderis swept or blown from the printing-form and the roller in no time, sothat the cleaning involves no difficulties.

For the object aimed at powder of corn or bolus alba has proved to bevery suitable for use as colouringmatter. It has also appeared to beadvantageous to use powder which has been statically charged beforehand.

In accordance with the invention the apparatus for carrying out themethodsaid apparatus being provided, just as that for applying ink onthe printing-form, with a roller, of which the surface is adapted tohold a layer of colouring-matter, and a device adapted toroll saidroller at an adjusted constant distance from a reference surface or theaxis of revolution of the cylindric supporting member over the surfaceof the supporting member or over the active surface of the layer orplate mounted on said member-may also be provided with a scraping membercooperating with said roller and so striking the layer of powder appliedon said roller as to make the surface of said layer exactly cylindricand concentric to the axis of revolution of said roller. For holding thepowder the roller may have a milled cylindric surface or be providedwith a fine gauze-shaped screen.

For the elucidation of the invention reference is made to theaccompanying drawing; therein is:

FIG. 1 an apparatus according to the invention for the examination ofthe flatness of flat printing-forms, and

FIG. 2 a like apparatus for the examination of the exact cylinder formof cylindric printing-forms.

In FIG. 1 a surface plate is designated by 1. Mounted above said plateis an exactly fiat plate 2 which is exactly parallel to said firstplate. The plate 2 is pivotally connected at 3 to supports 4 and restsin the operating position upon supports 5. When the plate 2 is swungaway (see the position in dotted lines) it is easy to secure thereto asupporting plate 6 provided with a printing block or form 7.

A sliding member 8 is mounted for reciprocation m the direction of thearrow 9 and back on said surface plate. Said sliding member carries aroller 1d of which the cylindric surface is milled in an extremely fineway. The roller it) is partly immersed in a trough it contain-' ingpowder 12, e.g. powder of corn or bolus alba. Cooperating With theroller it is a scraping knife 13 adapted to scrape the layer of powdertaken up by the roller during rotation of the roller, in such a manner,that the surface of said powder layer becomes exactly cylindric. Theroller 19 is rotatably supported by its shaft 14 between'arms 15 whichare pivotally connected about a shaft 16 to the sliding member 8. Withthe aid of an adjusting screw 17 the height of the roller can be exactlyadjusted.

The roller 10 is provided with a toothed wheel (not shown), of which thepitch circle is equal to that of the roller and a thin layer of powderprovided thereon. This toothed wheel meshes with a second toothed wheel18, which is mounted for rotation about the shaft 16 and comes tocooperate with a toothed rack 19 when the sliding member 8 is moved tothe left. It Will be a parent, that during further movement of thesliding member 8 the roller 10 and its layer of powder is rolled overthe printing block or form 7. Powder is then brought onto said block orform except in places which are too hollow.

In FIG. 2 the printing block '7 is mounted on a test cylinder or aprinting cylinder 2%. Said block may be securedto the test cylinder bymeans of suction. To a printing cylinder it may be attached or glued bynormal means. The powder roller is mounted for rotation directly on thesliding member 8. The roller it and the test or printing cylinder arecoupled by toothed wheels (not visible), in such a manner, that thelayer of powder is precisely rolled over the printing surface of theprint ing block 7 during rotation of the cylinder. As to the rest thereis hardly any difference in construction and operation with the deviceillustrated in FIG. 1.

What I claim is:

1. Method of locating low and high spots in printing surfaces comprisingthe steps of selecting a surface to he tested, applying an uninterruptedlayer of dry powder to the surface of a cylindric testing roller, makingthe outer surface of said layer exactly cylindric and concentric to theaxis of rotation of said roller and rolling said powdered roller oversaid surface to be tested while maintaining the axis of rotation of saidroller at constant distance from said surface to be tested, saiddistance being equal to the radius of the outer surface of said layer ofpowder.

2. The method set forth in claim 1 in which said powder is corn powder.

3. The method set forth in claim 1 in which said powder is bolus alba. v

4. The method set forth in claim 1 in which said powder is pigmented toreflect color.

5. A method of marking surfaces for printing purposes in order todetermine their accuracy comprising the steps of applying a layer ofpowder to the surface of a cyli'ndric test roller, forming the surfaceof said layer into a perfect cylinder concentric to the axis of saidroller, rolling said roller over said surface to be tested at a constantproximity thereto sufficient to apply small quantities of powder toaccurately formed portions of said surface, and noting portions of'saidsurface receiving different amounts of powder.

6. The method of marking surfaces for printing purposes in order todetermine their accuracy comprising the steps of applying to the surfaceof a cylindric testing roller a layer of dry powder having a cylindricalouter surface which is exactly concentric to the axis of rotation ofsaid roller, rolling said powder roller so said layer of powder is inlight kissing relation over the surface to be tested, whereby raisedportions of the latter surface receive a greater amount of powder thanlower portions thereof.

7. An apparatus for examining the flatness of a plane surface,comprising a roller having a surface adapted to hold a layer of powder,a doctor blade having an edge accurately positioned from the surface ofsaid roller, a

bin adapted to support powder in contact with said roller, meansmounting said roller for rotation to move, its

surface from said bin past said doctor blade to establish a constantthickness of powder on the surfaces of said roller, said powder having asurface concentric with the axis of said roller, slide means supportingsaid mounting means to move said roller across a plane surface at aconstant small distance therefrom, drive means to rotate said roller ata peripheral speed equivalent to the speed that said roller is movedacross said surface by said slide means, whereby said roller will applya greater amount of powder to raised portions of said surface and alesser amount of powder to lower portions thereof.

8. An apparatus for examining exactly the concentric cylinder shape of acylinder surface comprising a roller of known concentric cylinder shape,means mounting said roller for rotation about its axis, a bin positionedadjacent said roller and adapted to support powder in contact therewith,a straight edge positioned at predetermined small amounts from thesurface of said roller, means mounting said cylinder to be tested forrotation about its axis at a position in close proximity to saidfirstnamed roller its axis being parallel to said roller, and drivemeans interconnecting said rollers so that they rorate in oppositedirections at equal peripheral speed, said first-named roller rotatingin a direction that its surface moves consecutively from said doctorblade to said roller to be tested so a greater amount of powder isapplied to raised portions of said roller to be tested and a lesseramount of powder is applied to lower portions of said roller to betested.

9. An apparatus for testing for raised and lowered portions of a surfacecomprising a test roller of known concentric cylinder shape, a hopperadapted to support powder in contact with the surface of said testroller,

a doctor blade spaced a predetermined small distance from said roller,means to rotate said roller so that its surface passes through thepowder in said hopper and then past said doctor blade so that a layer ofpowder is deposited on said roller having a surface concentric to theaxis thereof, and said means for rotating said roller being thenconstructed to. drive said roller at equal surface speed over saidsurface to be tested and at a uniform spaced distance therefrom todeposit a greater quantity of powder on raised portions thereof and alesser quantity of powder to lower portions thereof within a narrowrange of variance.

References Cited in the file of this patent UNITED STATES PATENTS2,118,801 Banzett May 31, 1938 2,302,179 Bronfman Nov. 17, 19422,434,372 Stewart Ian. 13, 1948 2,811,465 Greig Oct. 29, 1957

1. METHOD OF LOCATING LOW AND HIGH SPOTS IN PRINTING SURFACES COMPRISINGTHE STEPS OF SELECTING A SURFACE TO BE TESTED, APPLYING AN UNINTERRUPTEDLAYER OF DRY POWDER TO THE SURFACE OF A CYLINDRIC TESTING ROLLER, MAKINGTHE OUTER SURFACE OF SAID LAYER EXACTLY CYLINDRIC AND CONCENTRIC TO THEAXIS OF ROTATION OF SAID ROLLER AND ROLLING SAID POWDERED ROLLER OVERSAID SURFACE TO BE TESTED WHILE MAINTAINING THE AXIS OF ROTATION OF SAIDROLLER AT CONSTANT DISTANCE FROM SAID SURFACE TO BE TESTED, SAIDDISTANCE BEING EQUAL TO THE RADIUS OF THE OUTER SURFACE OF SAID LAYER OFPOWDER.